a-a a-b a-c aaa aab aac aae aaf aah aao ab- aba abb abc abe abf abh abo ac- aca acb acc ace acf ach aco aea aeb aec aee aef aeh aeo af- afa afb afc afe aff afh afo aha ahb ahc ahe ahf ahh aho aoa aob aoc aoe aof aoh aoo baa bab bac bae baf bah bao bba bbb bbc bbe bbf bbh bbo bca bcb bcc bce bcf bch bco be- bea beb bec bee bef beh beo bfa bfb bfc bfe bff bfh bfo bha bhb bhc bhe bhf bhh bho boa bob boc boe bof boh boo c-- caa cab cac cae caf cah cao cba cbb cbc cbe cbf cbh cbo cca ccb ccc cce ccf cch cco ce- cea ceb cec cee cef ceh ceo cfa cfb cfc cfe cff cfh cfo ch- cha chb chc che chf chh cho co- coa cob coc coe cof coh coo eaa eab eac eae eaf eah eao eba ebb ebc ebe ebf ebh ebo ec- eca ecb ecc ece ecf ech eco eea eeb eec eee eef eeo ef- efa efb efc efe eff efh efo eha ehb ehc ehe ehf ehh eho eo- eoa eob eoc eoe eof eoh eoo faa fab fac fae faf fah fao fba fbb fbc fbe fbf fbh fbo fca fcb fcc fce fcf fco fea feb fec fee fef feh feo ffa ffc ffe fff ffh ffo fha fhb fhc fhe fhf fhh fho foa fob foc foe fof foh foo haa hab hac hae haf hah hao hba hbb hbc hbe hbf hbh hbo hca hcb hcc hce hcf hch hco he- hea heb hec hee hef heh heo hfa hfb hfc hfe hff hfh hfo hha hhb hhc hhe hhf hhh hho hoa hob hoc hoe hof hoh hoo oaa oab oac oae oaf oah oao ob- oba obb obc obe obf obh obo oc- oca ocb occ ocf och oco oea oeb oec oee oef oeh oeo of- ofa ofb ofc ofe off ofo oha ohc ohe ohf ohh oho oo- ooa oob ooc oof ooh ooo